Environmental conditioning system and method

ABSTRACT

An environmental conditioning method removes stale air and replaces it, at least in part, with fresh air at volumetric rates that are substantially the same. The stale air from the room is delivered to a return damper with a kinetic energy level of substantially zero, and the volumetric rate of airflow from and to the room is substantially independent of the volume of air removed and replaced. A modular damper unit may be employed, which provides heat exchangers for conservation of heat energy, and the system provided is readily adapted for centralized, overall environmental conditioning by the incorporation of heating, cooling, cleaning and humidity control means therein.

United States Patent [72] Inventor Davis I. Rawal 105 White St.,Waterbury, Conn. 06710 [21] Appl. No. 25,834 [22] Filed Apr. 6, 1970[45] Patented Nov. 9, 1971 [54] ENVIRONMENTAL CONDITIONING SYSTEM ANDMETHOD 10 Claims, 7 Drawing Figs.

[52] US. Cl 165/1, 165/3,165/16, 165/59, 165/107 [51] Int. Cl F28 [50]Field of Search 165/1-3, 16,59,66, 106, 107

[ 56] References Cited UNITED STATES PATENTS 1,895,444 1/1933 Cassell165/3 X 2,825,210 3/1958 Carr 165/66 X Primary Examiner-Carroll B.Dority, J r. A!t0rneyPeter L. Costas ABSTRACT: An environmentalconditioning method removes stale air and replaces it, at least in part,with fresh air at volumetric rates .that are substantially the same. Thestale air from the room is delivered to a return damper with a kineticenergy level of substantially zero, and the volumetric rate of airflowfrom and to the room is substantially independent of the volume of airremoved and replaced. A modular damper unit may be employed, whichprovides heat exchangers for conservation of heat energy, and the systemprovided is readily adapted for centralized, overall environmentalconditioning by the incorporation of heating, cooling, cleaning andhumidity control means therein.

PATENTEDunv 9 Ian 3151815 59 sum 1 [IF 3 REHEATING UNlT I30 I'ZBCOOLINOUNIT HUMIDIFIER I32 I26 FILTER H6 SECONDARY SUPPLY BLOWER \)34 R MARYRETURN BLOWER IZ4AIR CLEANER DAMPER UNIT l i :g s l M ifi jaa i FIG.7

//v VEN TOR [)A W5 1. A 4 h/AL ATTORNEY ENVIRONMENTAL CONDITIONINGSYSTEM AND METHOD BACKGROUND OF THE INVENTION In the design of effectiveventilation systems for homes, commercial buildings, and the like, thebasic objective is normally to attain a steady state condition whereinthe volumetric flow and exchange rates of air maintain the desiredambient conditions. Generally, present systems simply rely upon fans andblowers to achieve air exhaust, as a result of which the mere act ofopening a door or a window affects the operation of the system andchanges the ventilation characteristicsr moreover, such systems tend toinduce drafts and often undesirably affect conditions in areas adjacentto that being ventilated. A separate makeup air unit may be installed tocounteract these effects and to ensure positive ventilation, but thistends to be costly and inconvenient since the fresh air must be heated,cooled, or otherwise conditioned to maintain the area at a comfortabletemperature, humidity level, etc.

These problems are well known, and various attempts have been made tosolve them. For example, devices are described in the art which may beused to recycle a portion of the room air in an effort to conserve heatenergy. However, so far as is known, no system has been heretoforedesigned that permits a wide latitude of variation in the proportion ofair recycled (or conversely, exhausted), while at the same timemaintaining a substantially constant flow rate of air through thesystem, or that operates in such a manner substantially independently ofthe availability of air access points, such as through windows, doors,etc.

Accordingly, the primary object of the present invention is to provide anovel environmental conditioning method wherein all, none, or a portionof the air exhausted from an area may be replaced with fresh air withoutappreciable afiect upon the volumetric flow rate through the conditionedarea.

It is also an object of the invention to provide such method wherein therate of air removal is substantially the same as the rate of return, andthe rate of ventilation is substantially independent of changes in thepositions of doors, windows, etc. within the ventilated area.

Another object is to provide a modular damper unit that may be employedtherein to control the condition of the air within an area and tofurnish air at a temperature approximating ambient, in an economicalmanner by conservation of the heat content of air exhausted therefrom.

SUMMARY OF THE INVENTION It has now been found that the foregoing andrelated objects can be readily attained in a method of environmentalconditioning wherein stale air is continuously removed from aconditioned area at a preselected volumetric rate, and delivered througha conduit to the vicinity of a variable return damper at a kineticenergy level of substantially zero. A variable exhaust opening in theconduit upstream of the damper is controlled to discharge an appropriatevolume of the stale air therethrough, and the return damper iscontrolled to permit recycle of the remainder of the stale airtherethrough and into a second conduit communicating with theconditioned area. A variable intake opening that is located in thesecond conduit downstream of the damper and in the vicinity thereof iscontrolled to admit therethrough a volume of fresh air that issubstantially equal to the volume of stale air that is discharged. Thevolume of fresh air and the air recycled is withdrawn from the vicinityof the damper and a mixture thereof is continuously delivered to theconditioned area through the second conduit; the volumetric rate ofdelivery is substantially the same as the preselected volumetric rate ofremoval of stale air, and is substantially independent of the volume ofair that is discharged.

In the preferred method, the stale air and the fresh air are atdifferent temperatures, and the temperature desired in the mixturedelivered to the conditioned area is intermediate thereof. The volume ofair discharged and admitted is controlled to provide proportions offresh and recycle air in the mixture that are appropriate to attain thedesired temperature therein. In such a case, the method may include theadditional step of extracting a portion of the heat energy fromwhichever one of the discharged and admitted volumes is warmer, andtransferring the heat energy to the cooler one thereof. A temperaturedependent signal may be generated for automatic control for the volumeof air discharged and admitted, and the stale air may be cleaned toremove pollutants therefrom before it is delivered to the return damperand before the volume thereof is discharged.

The present invention also provides an environmental conditioning systemutilizing a modular damper unit that comprises a housing providing aflow chamber that has an inlet opening for receiving air from aconditioned area, an outlet opening for returning air thereto, anexhaust opening for discharging air from the system, and an intakeopening for drawing fresh'air thereinto. A return damper in the housingsubstantially divides the chamber into two parts, the inlet and exhaustopenings communicating with one of the parts and the outlet and intakeopenings communicating with the other part thereof; direct airflowbetween the parts is substantially blocked by the damper in the closedposition thereof. At least one additional damper in the housing thatoverlies the exhaust and intake openings substantially blocks airflowtherethrough when in the closed position thereof. Control means isprovided to drive the dampers and to operatively couple them together insuch a manner that when one of the dampers is moved from the closedposition to the open position thereof, the other one of the dampers ismoved from the open position to the closed position thereof. The unitalso includes a heat exchanger that is comprised of a heat exchangemember overlying each of the exhaust and intake openings, and a pump forcirculating heat exchange fluid through the heat exchanger from one ofthe members to the other. Heat is thereby extracted from air passingthrough one of the exhaust and intake openings and is dissipated tocooler air passing through the other one thereof, when the additionaldamper is in an open position.

In the preferred embodiments, the system additionally includes anupstream conduit connected to the inlet opening of the flow chamber forconveying air thereto, and a downstream conduit connected to the outletopening of the flow chamber for conveying air therefrom. A blower in theupstream conduit induces air flow toward the damper unit and a blower inthe downstream conduit induces air flow therefrom, the upstream blowerbeing sized and powered to deliver air to the return damper at a kineticenergy level ofsubstantially zero. The dampers and openings arecooperatively dimensioned and configured so that the downstream blowerdraws air at substantially the same volumetric rate through the returndamper, when the additional damper is in closed position, and throughthe intake opening, when the return damper is in the closed positionthereof. Most desirably, the blowers are relatively sized and powered toprovide substantially the same volumetric rate of air flow at the outerextremities of the upstream and downstream conduits. The system mayinclude a temperature sensor having means for generating a temperaturedependent signal, the control means in the damper unit beingautomatically responsive to the signal from the generating means todrive the dampers in such a manner as will tend to substantiallymaintain a desired preselected temperature in air flowing past theextremity of the downstream conduit. It may also include anelectrostatic precipitator upstream of the exhaust outlet to ensure thatrecycled and exhausted portions of the air from the conditioned areacontain a reduced concentration of pollutants.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of adamper unit embodying the present invention, a portion of the housingbeing broken away to show the inner construction thereof;

FIG. 2 is a schematic elevational view of an installed environmentalconditioning system incorporating such a damper unit;

FIG. 3 is a plan view of the system of FIG. 2;

FIGS. 4, 5 and 6 are side elevational views of the damper unitillustrated in FIG. 1, to a reduced scale, showing positions to whichthe dampers therein may be adjusted and illustrating the air flowconfigurations resulting therefrom; and

FIG. 7 is an elevational view of a second system incorporating the typeof damper unit illustrated in FIG. 1 and providing a unified overallenvironmental conditioning system.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Turning now indetail to FIG. 1 of the appended drawings, a damper unit embodying thepresent invention and generally designated by the numeral 10 isillustrated therein, and comprises a rectangular housing 11 having aninterior vertical partition 12 which divides it transversely into a flowchamber portion 14 and a central chamber portion 16. Each of thesidewalls 18 thereof has a large rectangular opening 20, 20therethrough, providing an inlet to, and an outlet from, the flowchamber portion 14, respectively; the openings 20, 20' have flanges 22projecting outwardly thereabout to facilitate attachment to connectingconduits in a conventional manner. A longitudinal vertical partition,generally designated by the numeral 24, divides the unit 10 between oneend wall 26 and the transverse partition 12, and consists of a solidlower portion 26 and a vertical return damper assembly 28 thereabove.The damper assembly 28 consists, in a conventional manner, of amultiplicity of pivotally mounted horizontally extending blades or slats30, the lowermost one 30 of which has an axially extending shaft 32 onwhich is secured a drive sprocket 34. The remaining slats 30 areoperatively connected to the slat 30' (by means not shown) so thatpivotal movement thereof, through the sprocket 34 and shaft 32, istransmitted to all of the slats 30 to pivot them concurrently.

The bottom wall 36 of the housing 11 has formed therein, on one side ofthe longitudinal partition 24, an exhaust opening 38 and, on theopposite side of the partition 24, a makeup or intake In lieu of anexisting fan (such as 78 in FIG. 2) thepresentsystem includes a primaryreturn blower 118, which serves to draw the stale air out of the room120 and through both the conduil22 and the electrostatic air cleaner124, and to deliver it with substantially no kinetic energy at thedamper 28 of the unit 10. Theblower 118 and the air cleaner 124 aresupported on the stand 114 on the upstream or exhaust side of the damperunit 10, and on thedownstream or intake side thereofa filter 126, acooling unit 128, a reheating unit 130, a humidifier 132 and secondarysupply blower 135 are supported in serial registry. As in the systempreviously described, the blower 134 draws fresh and.or recycle airthrough the damper unit 10, and in the present system it thereafterdraws the air through the cooling unit 128, reheating unit 130 andhumidifier 132; finally, the blower 134 supplies the air to the room 120through the return conduit 136. Accordingly, thisystem may berelied uponforcomplete environmental control, having not only the capcbility oftotally exhausting, totally recycling, or partially recycling stale roomair and replacing it with a desired proportion offresh air, but it mayalso be used for primary temperature andhumidity control; moreover, allof these functions may be automatically controlled and balanced foroptimum environmental conditionsby suitable and appropriately locatedsensors. It will beapparent that in this embodiment, the reheating unit130 is an electric, steam or gas fired device, and that the cooling unitmay operate on conventional air conditioner" principles. Other devicesmay be included therein, and the possibilites in this regardwillbeapparent to those skilled in the art.

Normally, the systems of the invention will be designed to provide theparticular volumetric flow rate of air through the conditioned area thathas been determined to best afford the desiredlevel of ventilation;thimay be accomplished by balancing the capacity of the blowers againstthe static head or resistance oftye syetem. As has been pointed outpreviously, it

ismost advantageous to deliver the air from the room to the returndamperwith a kinetic energy approaching, or very nearly, zero. Thisassumes that such will also be the prevailing condition of theoutsideair, so that at the return baffle thedownstream blower willdraisubstantially the same volume of air per unit of time, regardless ofwhether it draws the air from outside or from theupstream side of thereturn damper.

These objectives can most simply be attained by dimensioning andconfiguring the dampers and the openings covered thereby so that theunobstructed areas thereof are of approximately the same size. In such acase, balancing of the system t achieve a constant flow rate of air andan equal exhaust and return rate to the room will be simplifiedconsiderably. As a practical manner, if the unobstructed areas are nounduly small, in many instanceteh specific size thereof becomes ofsecondary importance. In any event, the simplest manner of designandinstallation will usually entail a rough approximation of thespecifications necessary to achieve adequate ventilation and, afterinstallation, registration of the drivepower for the blowers until thesystem is satisfactorily balanced. It should be appreciated that theterm blowers" has been used herein for the sake of convenience and isintended to encompass any device that may be appropriate to induceairflow; ithas also been usedwithout regard for whether its primaryfunction is one f suction r0 of blowing of air. Similarly, conservationof heat content has been usedin the sense that the negative ofdeficiency of heat energy of air cooled relative to ambient may beconserved, just as may the real energy of relatively warm air. Inaddition, although it has been stressed that the total volumetric rateof airflow through the return and additional dampers shouldbesubstantially the same regardless of which isopen and which is closedthe damper design will usually be such as to cooperatively affordsubstantially that rate when both of them arein appropriate partiallyopen positions.

It will be appreciated for the foregoing that the present inventionembodies the novel concept of effecting an exchange of air by exhaustingstale air at substantially the same energy level as thatat which thefresh air, used for replacement thereof, exists. Thus, the ambient airis assumed to have a kinetic energy level of substantially zero and, bydelivering the stale air to the return dampera at about the same energylevel, the downstream blower will remove the same volume of airtherefrom regardless of whether the air removedconsists of fresh air,stale air, or a mixture containing any proportion thereof. Since thisresult may generally be realized even though the staleair arrives at thereturn damper with a level of kineticenergy somewhat above zero, theterm kinetic energy level ofsubstantially zero should be understood tomean that the stale air would arrive at the damper but eave little or notendency to pass therethrough in the absence of the effect of thedownstream blower thereon.

Thus, it can be seen that the present invention provides anenvironmental conditioning method wherein all, one, or a portion of theair exhausted from an area may be replaced with fresh air withoutappreciable affect upon the volumetric flow rate through the conditionedares. In the method, the rate of air removal is substantially the sameas the rate of return thereof and the rate of ventilation issubstantially independent of changes in the positions ofdoors, windows,etc. within the ventilated area. A modular damperunit controls thecondition of the air within an area to furnish air a a temperatureapproximating ambient, in an economical manner by conservation of theheat ocntent of air exhausted from the conditioned area.

Having thus described the invention l CLAIM:

I. In a method of environmental conditioing, the steps comprising:

A. continuously removing staleair from a conditionedarea at apreselected volumetric rate and deliveringitthrough a conduit to thevicinity of a variablereturn damper at a kinetic energy level ofsubstantially zero;

B. controlling a variableexhaust opening in saiconduit upstrea of saiddaper t discharge an appropriate volume f said stale air therethrugh;

C. controlling said return damper t permit recycle of the remainder ofsaid stale air therethrough and into a second conduitcommunicating withsaid conditioned area;

D. controlling a variableintakeopenin, located in said second conduitdownstream of said damper and in the vicinity thereof, to admittherethrough a volume offresh air substantially equal to said volume fstale air discharged; and

E. withdrawing said volume of fresh air and said recycle air from thevicinity of said damper and continuously delivering a mxiture thereof tosaid conditioned area through said second conduit at substantially saidpreselected volu metric rate, said volumetric rate being substantiallyindependent of said volume of air discharged.

2. The method of claim 1 wherein said stale air an saidfresh air are atdifferent temperatures, wherein wherein the temperature desired insaidmixture is intermediate thereof, and wherein said volume of airdischarged and admitted is controlled to provide proportions of freshandrecylce air in said mixture appropriate to attain said desiredtemperature therein.

3. The method of claim 2 including the additional step of extracting aportion of the heat energy from the warmer of said discharged volume andsaid admitted volume, and transferring saidheat energy to the cooler onethereof.

4. The method of claim 2 additionally including the step of generating atemperature dependent signal responsive to the temperature in saidconditioned area has been inserted for automatic control of said volumeof air discharged and admitted.

5. The method of claim 1 including the additional step of cleaning saidstale air to remove pollutants therefrom before delivery to said returndamper anddischarge of said volume thereof.

6. in an environmental conditining system, a modular damper unitcomprising: A. a housing;

B. a flow chamber in said housing having an inletopening for receivingair from a conditioned area, an outlet opening forreturning air thereto,an exhaust openingfor discharging air from said system, and an intakeopening for drawing fresh air thereinto;

C. a return damper in said housing substantially dividing said chamberinto two parts, said inlet and exhaust openings communicating with oneof said parts and said outlet and intakeopenings communicating with theother part thereof, direct air flow between said parts beingsubstantially blocked by said damper in the closed position thereof;

D. at least one additional damper in said housing overlying said exhaustand intake openings, airflow therethrough being substantially blocked bysaid additional damper in the closedposition thereof;

E. control means for driving said dampers anoperatively coupling themtogether in such a manner thatwhen one of said dampers is moved fromsaid closedposition to the open position thereof the other one of saiddampers is moved from the open position to said closedposition thereof;an

F. a heat exchanger comprising aheat exchangemember overlying each ofsaid exhaust and intakeopeningsand a pump for circulating a heatexchange fluid through said heat exchanger for ne of said members t thethere whereby heat is extracted from airpassingthrugh one of saidexhaustandintakeopenings and idissipated t cooler air passing through the otherone thereof, when said additional damper is in an open position.

7. The system of claim 6 additionally including: an upstream conduitconnected to said inlet opening of said flow chamber for conveying airthereto; a downstream conduit connected to said outlet opening of saidflow chamber for conveying air therefrom; a blower in said upstreamconduit forinducing airflow toward said unit; and a blower in saiddownstream conduit forinducing airflow from said unit; said upstreablwer being sized andpowered to deliver air to said return damper at akinetic energy level of substantially zer, and saiddampers and openingsbeing cooperatively dimensioned and configured for said downstreamblower to draw airat substantially the samevolumetric rate through saidreturn damper when said additional damper is in closed position andthrough said intake opening when saidreturn damper is in saidclosedposition thereof.

8. The system of claim 7 wherein said blowers are relatively sizedandpowered to provide substantially the same volumetricrate ofairflow atthe outer extremities of said upstream and dwnstream conduits.

9. The system of claim 8 including a temperature sensorhaving means forgenerating a temperature dependent signal, said control means beingautoatically responsive to the signal from saidgenerating means to drivesaid dampers in such a manner as will tendto substantially maintain adesired preselected temperature in air flowing past the said extremityof said downstream conduit.

10. The system of claim 8 additionally including anelectrostaticprecipitator upstream of said exhaust outlet tensurethatrecycled and exhaustedportions of the air from the conditionedarea contain a reduced concentration ofpollutants. opening 40. Each ofthese openings 38, 40 is covered by a horizontal damper assembly 42,comprised of a multiplicity of pivotally mounted, operatively connected,horizontally extending slats 44, the inner ones 44' of which haveaxially extending shafts 46 on which are secured drive sprockets 48. Amotor 50 is supported upon the bottom wall 36 of the housing 11, and ithas a shaft 52 with a sprocket 54 affixed adjacent the outer endthereof. A common drive chain 56 is engaged over each of the sprockets34, 48, 54, so that actuation of the motor 50 simultaneously operatesall of the dampers 28, 42.

Heat exchanger members, generally designated by the numeral 58, extendhorizontally over each of the dampers 42, and consist of a multiplicityof thin vertical radiator fins 60, extending between the vertical wall24 and the sidewalls l8, and a continuous coil 62 that is convoluted toprovide elements 64 passing longitudinally back and forth through eachof the members 58. The elements 64 of one of the heat exchanger members58 are connected to those of the other by a central element 66, and theopposite ends thereof are connected to an electrically operated pump 68that is supported upon the bottom wall 36 of the housing 11. As will beap parent, heat exchange fluid may be forced through the tube 62 fromone heat exchanger member 58 to the other by operation of the pump 68,as will be more fully explained hereinafter.

Turning now to FIGS. 2 and 3 of the drawings, the damper unit 10hereinbefore described is shown in a kitchen ventilating system, whichmay in part utilize existing equipment. Thus, the kitchen 70 contains acooking range 72, above which is installed a hood 74 for the collectionof grease, fumes and the like. A removable filter 76 is supported withinthe hood 74, and a fan 78 is mounted thereabove to withdraw the staleair through the filter 76 and out of the room 70 through the hole 80provided in the roof 82 thereof. The damper unit 10 is provided with adepending baffle 81 between the exhaust opening 38 and makeup opening 40thereof, and it is supported over the roof 82 upon a suitable anglestand 84. The stand 84 also supports a blower 86 and an electrostaticcleaner 88, the former having a removable weather cap 89 thereon andbeing connected to the outlet opening 20' from the flow chamber portion14 of the housing 10, and the latter being connected to the inletopening 20 thereof. A plenum chamber 90 is mounted directly over theroof hole 80, and it has connected to it a short horizontal conduit 92directed toward the electrostatic cleaner 88; interposed between thecleaner 88 and the conduit 92 is a wash manifold 94, used for periodicwashing of the electrostatic cleaner 88. An angled conduit 96 isconnected to the outlet side of the blower 86 with the vertical leg 98thereof passing through a second hole 100 in the roof 82 and a curb 102thereabove, the curb 102 having a suitable protective flange or skirt104 extending about it. The leg 98 of the conduit 96 opens into ahorizontally extending duct 106 that has a multiplicity of outletregisters 108 spaced along its length. A wall-mounted thermostat 110senses the temperature in the kitchen 70 and controls operation of theventilating system in a manner to be described.

In operation of the system depicted in FIGS. 2 and 3, the fan 78 drawsstale air upwardly from the kitchen 70 through the filter 76, anddelivers it through the electrostatic cleaner 88 to the inlet side ofthe damper unit 10, preferably so that it arrives thereat withsubstantially no kinetic energy. Thus, the fan 78 is preferably sizedand powered sufi'lciently to just overcome the static resistance of theexhaust portion of the system upstream of the damper 28. Similarly, theblower 86 is sized and powered to overcome the static resistance of themakeup portion on the opposite or downstream side of the system, and toequalize the pressure in the kitchen 70 by providing a volumetric flowof makeup air through the registers 108 sufficient to just balance thevacuum created by the fan 78. In this manner, a steady state conditioncan be attained substantially without drafts, even though the positionsof kitchen doors and windows be altered.

Depending upon the temperature of the outside air, and with particularreference to FIGS. 4-6 of the drawings, the position of the dampers inthe damper unit may be automatically controlled to maintain a desiredtemperature within the room, in an economical manner and withoutcreating undesirable drafts therethrough. In FIG. 4, the slats 30 of thevertical bypass damper assembly 28 are aligned horizontally in fullyopen position, and the slats 44 of the horizontal damper assemblies 42are at right angles to one another so that the edges of adjacent slats44 are in contact to close the assemblies 42. As a result, all of theair from the room 70 is recycled and no fresh air is taken in, thusmaintaining the room temperature with a minimum level of heat loss orgain, as is desirable to conserve the energy needed to heat or cool theroom, as the case may be.

In FIG. 5, the converse situation is depicted wherein the edges of theslats 30 are in contact to close the damper assembly 28, and the slats44 are aligned vertically in fully open position of the dampers 42. Itwill be apparent that in these positions the air withdrawn from the room70 is totally expelled and replaced by fresh outside air; this conditionis appropriate when the temperature outside the room is substantiallythe same as that which it is desired to maintain therewithin.

Finally, FIG. 6 illustrates one of an infinite number of intermediatearrangements of damper slats wherein each of the damper assemblies 28,42 is partially open. This permits a portion of the stale air to beexhausted and replaced with fresh air, the remainder thereof beingrecycled to the room. Such an arrangement is appropriate under a varietyof circumstances, one example of which occurring when the heat withdrawnover a cooking range would unduly raise the room temperature if totallyrecycled; dilution thereof with cooler outside air may be relied upon tomaintain the temperature at a desirable level, while at the same timefreshening the atmosphere in the room.

It will be appreciated that the position of the dampers 28, 42 isthermostatically controlled by the thermostat 110, which is designed totransmit (such as through a proportioning device, not shown) anappropriate signal to the motor 50 that drives the slats 30, 44.Although the thermostat 110 may be wall mounted, as shown in FIG. 2, itmay be more efficient, in terms of accuracy and responsiveness ofcontrol, to mount it within the duct 106 or conduit 96 since the airtherein will be at virtually one temperature and not subject todilution, as would normally be the case within the room 70.

It will also be appreciated that since the stale air from the room isdelivered to the damper unit at a substantially zero kinetic energylevel, the volume of air recycled by the blower 86 will be independentof the position of the dampers 28, 42; i.e., both room air and fresh airat the damper unit will be at substantially the same pressure.Accordingly, if the fan 78 and blower 86 are properly sized and powered,the system will operate virtually draft-free, regardless of the positionof dampers, doors, windows, etc.

The heat exchanger members 58 shown in FIG. 1 of the drawings are ofsignificant value in obtaining the maximum effectiveness and economyfrom the damper unit 10. It will be apparent that in pumping the heattransfer fluid from one of the members 58 to the other, the heat fromthe warmer air passing through one side of the damper unit can berecovered and dissipated to the cooler air passing through the otherside thereof. Thus, when the exhaust air flowing through the inletopening 20 and the exhaust opening 38 of the unit 10 is at an elevatedtemperature relative to outside air, the heat exchanger members 58 maybe used to recover its heat and transfer it to the fresh air passingthrough the intake opening 40 and outlet opening 20' thereof. Similarly,if the inside air is cooler than the outside air, the members 58 may beused to cool the incoming air, and thereby reduce the load upon theequipment used to cool the room. Accordingly, the principal benefitderived from operation with heat exchange is the capability of drawing asignificant quantity of fresh air into the room while at the same timemaintaining the temperature therein with a minimum increase in thedemand upon the heating or cooling equipment.

Turning finally to FIG. 7, the system therein illustrated is suitablefor installation where no previous exhaust system was present, and itincorporates a number of features absent from the system depicted inFIG. 2. The damper unit 10, which is supported over the roof 112 upon asuitable support stand 114, is once again the heart of the system and isvirtually the same as that shown in FIG. 1. However, in the present unit10 an alternate exhaust opening is provided by the duct I16 (illustratedin phantom line) which is positioned at the top of the unit remote fromthe intake opening 40 at the bottom thereof. This renders the baffle 81unnecessary since it ensures that the exhaust air will not be drawnimmediately back into the unit; accordingly, when the duct 116 replacesthe exhaust opening 38, the baffle 81 may be eliminated.

In lieu of an existing fan (such as 78 in FIG. 2) the present systemincludes a primary return blower 118, which serves to draw the stale airout of the room 120 and through both the conduit 122 and theelectrostatic air cleaner 124, and to deliver it with substantially nokinetic energy at the damper 28 of the unit 10. The blower 118 and theair cleaner 124 are supported on the stand 114 on the upstream orexhaust side of the damper unit 10, and on the downstream or intake sidethereof a filter 126, a cooling unit 128, a reheating unit 130, ahumidifier 132 and secondary supply blower 134 are supported in serialregistry. As in the system previously described, the blower 134 drawsfresh and/or recycle air through the damper unit 10, and in the presentsystem it thereafter draws the air through the cooling unit 128,reheating unit and humidifier 132; finally, the blower 134 supplies theair to the room 120 through the return conduit 136. Accordingly, thissystem may be relied upon for complete environmental control, having notonly the capability of totally exhausting, totally recycling, orpartially recycling stale room air and replacing it with a desiredproportion of fresh air, but it may also be used to primary temperatureand humidity control; moreover, all of these functions may beautomatically controlled and balanced for optimum environmentalconditions by suitable and appropriately located sensors. It will beapparent that in this embodiment, the reheating unit 130 is an electric,steam or gas fired device, and that the cooling unit may operate onconventional air conditioner principles. Other devices may be includedtherein, and the possibilities in this regard will be apparent to thoseskilled in the art.

Normally, the systems of the invention will be designed to provide theparticular volumetric flow rate of air through the conditioned area thathas been determined to best afford the desired level of ventilation;this may be accomplished by balancing the capacity of the blowersagainst the static head or resistance of the system. As has been pointedout previously, it is most advantageous to deliver the air from the roomto the return damper with a kinetic energy approaching, or very nearly,zero. This assumes that such will also be the prevailing condition ofthe outside air, so that at the return baffle the downstream blower willdraw substantially the same volume of air per unit of time, regardlessof whether it draws the air from outside or from the upstream side ofthe return damper.

These objectives can most simply be attained by dimensioning andconfiguring the dampers and the openings covered thereby so that theunobstructed areas thereof are of approximately the same size. In such acase, balancing of the system to achieve a constant flow rate of air andan equal exhaust and return rate to the room will be simplifiedconsiderably. As a practical manner, if the unobstructed areas are notunduly small, in many instances the specific size thereof becomes ofsecondary importance. In any event, the simplest manner of design andinstallation will usually entail a rough approximation of thespecifications necessary to achieve adequate ventilation and, afterinstallation, registration of the drive power for the blowers until thesystem is satisfactorily balanced. It should be appreciated that theterm blowers has been used herein for the sake of convenience and isintended to encompass any device that may be appropriate to induceairflow; it has also been used without regard for whether its primaryfunction is one of suction or of blowing of air. Similarly, conservationof heat content" has been used in the sense that the negative ordeficiency of heat energy of air cooled relative to ambient may beconserved, just as may the real energy of relatively warm air. Inaddition, although it has been stressed that the total volumetric rateof airflow through the return and ad ditional dampers should besubstantially the same regardless of which is open and which is closed,the damper design will usually be such as to cooperatively affordsubstantially that rate when both of them are in appropriate partiallyopen positions.

It will be appreciated from the foregoing that the present inventionembodies the novel concept of effecting an exchange of air by exhaustingstale air at substantially the same energy level as that at which thefresh air, used for replacement thereof, exists. Thus, the ambient airis assumed to have a kinetic energy level of substantially zero and, bydelivering the stale air to the return damper at about the same energylevel, the downstream blower will remove the same volume of airtherefrom regardless of whether the air removed consists of fresh air,stale air, or a mixture containing any proportion thereof. Since thisresult may generally be realized even though the stale air arrives atthe return damper with a level of kinetic energy somewhat above zero,the term kinetic energy level of substantially zero should be understoodto mean that the sale air would arrive at the damper but have little orno tendency to pass therethrough in the absence of the effect of thedownstream blower thereon.

Thus, it can be seen that the present invention provides anenvironmental conditioning method wherein all, none, or a portion of theair exhausted from an area may be replaced with fresh air withoutappreciable affect upon the volumetric flow rate through the conditionedarea. In the method, the rate of air removal is substantially the sameas the rate of return thereof and the rate of ventilation issubstantially independent of changes in the positions of doors, windows,etc. within the ventilated area. A modular damper unit controls thecondition of the air within an area to furnish air at a temperatureapproximating ambient, in an economical manner by conservation of theheat content of air exhausted from the conditioned area.

Having thus described the invention, 1 claim:

1. In a method of environmental conditioning, the steps comprising;

A. continuously removing stale air from a conditioned area at apreselected volumetric rate and delivering it through a conduit to thevicinity of a variable return damper at a kinetic energy level ofsubstantially zero;

B. controlling a variable exhaust opening in said conduit upstream ofsaid damper to discharge an appropriate volume of said stale airtherethrough;

C. Controlling said return damper to permit recycle of the remainder ofsaid stale air therethrough and into a second conduit communicating withsaid conditioned area;

D. controlling a variable intake opening, located in said second conduitdownstream of said damper and in the vicinity thereof, to admittherethrough a volume of fresh air substantially equal to said volume ofstale air discharged; and

E. withdrawing said volume of fresh air and said recycle air from thevicinity of said damper and continuously delivering a mixture thereof tosaid conditioned area through said second conduit at substantially saidpreselected volumetric rate, said volumetric rate being substantiallyindependent of said volume of air discharged.

2. The method of claim 1 wherein said stale air and said fresh air areat different temperatures, wherein the temperature desired in saidmixture is intermediate thereof, and wherein said volume of airdischarged and admitted is controlled to provide proportions of freshand recycle air in said mixture appropriate to attain said desiredtemperature therein.

3. The method of claim 2 including the additional step of extracting aportion of the heat energy from the warmer of said discharged volume andsaid admitted volume, and transferring said heat energy to the coolerone thereof.

4. The method of claim 2 additionally includingthe step of generating atemperature dependent signal responsive to the temperature in saidconditioned area for automatic control of said volume of air dischargedand admitted.

5. The method of claim 1 including the additional step of cleaning saidstale air to remove pollutants therefrom before delivery to said returndamper and discharge of said volume thereof.

6. In an environmental conditioning system, a modular damper unitcomprising:

A. a housing;

B. a flow chamber in said housing having an inlet opening for receivingair from a conditioned area, an outlet opening for returning airthereto, an exhaust opening for discharging air from said system, and anintake opening for drawing fresh air thereinto;

'C. a return damper in said housing substantially dividing said chamberinto two parts, said inlet and exhaust openings communicating with oneof said parts and said outlet and intake openings communicating with theother part thereof, direct airflow between said parts beingsubstantially blocked by said damper in the closed position thereof;

D. at least one additional damper in said housing overlying said exhaustand intake openings, airflow therethrough being substantially blocked bysaid additional damper in the closed position thereof;

E. control means for driving said dampers and operatively coupling themtogether in such a manner that when one of said dampers is moved fromsaid closed position to the open position thereof the other one of saiddampers is moved from the open position to said closed position thereof;and

F. a heat exchanger comprising a heat exchange member overlying each ofsaid exhaust and intake openings and a pump for circulating a heatexchange fluid through said heat exchanger from one of said members tothe other, whereby heat is extracted from air passing through one ofsaid exhaust and intake openings and is dissipated to cooler air passingthrough the other one thereof, when said additional damper is in an openposition.

7. The system of claim 6 additionally including: an upstream conduitconnected to said inlet opening of said flow chamber for conveying airthereto; a downstream conduit connected to said outlet opening of saidflow chamber for conveying air therefrom; a blower in said upstreamconduit for inducing airflow toward said unit; and a blower in saiddownstream conduit for inducing airflow from said unit; said upstreamblower being sized and powered to deliver air to said return damper at akinetic energy level of substantially zero, and said dampers andopenings being cooperatively dimensioned and configured for saiddownstream blower to draw air at substantially ill said control meansbeing automatically responsive to the signal from said generating meansto drive said dampers in such a manner as will tend to substantiallymaintain a desired preselected temperature in air flowing past the sameextremity of said downstream conduit.

10. The system of claim 8 additionally including an electrostaticprecipitator upstream of said exhaust outlet to ensure that recycled andexhausted portions of the air from the conditioned area contain areduced concentration of pollutants.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENTNO. 3,618,659

DATED November 9, 1971 INVENTORiS) Davis I. Rawal It is certified thaterror appears in the above-identified patent and that said LettersPatent is hereby corrected as shown below:

Column 3, line 40, delete the material begin ing with "In lieu of"through columns 4, 5 and 6 to line 23 ending with the words ofpollutants".

Signed and Scaled this Fifteenth Day of May 1984 [SEAL] A nest:

GERALD J. MOSSINGHOFF Arresting Offlccr Commissioner ofl'amm andTrademarks

2. The method of claim 1 wherein said stale air and said fresh air areat different temperatures, wherein the temperature desired in saidmixture is intermediate thereof, and wherein said volume of airdischarged and admitted is controlled to provide proportions of freshand recycle air in said mixture appropriate to attain said desiredtemperature therein.
 3. The method of claim 2 including the additionalstep of extracting a portion of the heat energy from the warmer of saiddischarged volume and said admitted volume, and transferring said heatenergy to the cooler one thereof.
 4. The method of claim 2 additionallyincluding the step of generating a temperature dependent signalresponsive to the temperature in said conditioned area for automaticcontrol of said volume of air discharged and admitted.
 5. The method ofclaim 1 including the additional step of cleaning said stale air toremove pollutants therefrom before delivery to said return damper anddischarge of said volume thereof.
 6. In an environmental conditioningsystem, a modular damper unit comprising: A. a housing; B. a flowchamber in said housing having an inlet opening for receiving air from aconditioned area, an outlet opening for returning air thereto, anexhaust opening for discharging air from said system, and an intakeopening for drawing fresh air thereinto; C. a return damper in saidhousing substantially dividing said chamber into two parts, said inletand exhaust openings communicating with one of said parts and saidoutlet and intake openings communicating with the other part thereof,direct airflow between said parts being substantially blocked by saiddamper in the closed position thereof; D. at least one additional damperin said housing overlying said exhaust and intake openings, airflowtherethrough being substantially blocked by said additional damper inthe closed position thereof; E. control means for driving said dampersand operatively coupling them together in such a manner that when one ofsaid dampers is moved from said closed position to the open positionthereof the other one of said dampers is moved from the open position tosaid closed position thereof; and F. a heat exchanger comprising a heatexchange member overlying each of said exhaust and intake openings and apump for circulating a heat exchange fluid through said heat exchangerfrom one of said members to the other, whereby heat is extracted fromair passing through one of said exhaust and intake openings and isdissipated to cooler air passing through the other one thereof, whensaid additional damper is in an open position.
 7. The system of claim 6additionally including: an upstream conduit connected to said inletopening of said flow chamber for conveying air thereto; a downstreamconduit connected to said outlet opening of said flow chamber forconveying air therefrom; a blower in said upstream conduit for inducingairflow toward said unit; and a blower in said downstream conduit forinducing airflow from said unit; said upstream blower being sized andpowered to deliver air to said return damper at a kinetic energy levelof substantially zero, and said dampers and openings being cooperativelydimensioned and configured for said downstream blower to draw air atsubstantially the same volumetric rate through said return damper whensaid additional damper is in closed position and through said intakeopening when said return damper is in said closed position thereof. 8.The system of claim 7 wherein said blowers are relatively sized andpowered to provide substantially the same volumetRic rate of airflow atthe outer extremities of said upstream and downstream conduits.
 9. Thesystem of claim 8 including a temperature sensor having means forgenerating a temperature dependent signal, said control means beingautomatically responsive to the signal from said generating means todrive said dampers in such a manner as will tend to substantiallymaintain a desired preselected temperature in air flowing past the sameextremity of said downstream conduit.
 10. The system of claim 8additionally including an electrostatic precipitator upstream of saidexhaust outlet to ensure that recycled and exhausted portions of the airfrom the conditioned area contain a reduced concentration of pollutants.